Happy St Patrick's Day!

In honor of St Patrick's day and all things green, I give you the PCB...

And some trivia. You may have noticed that the soldermask used on most PC boards is green, as is the paint used on most steel truss bridges. Why is that? And what do the two things have in common? Why green PCBs and why green bridges?

To answer, I brought in color expert expert Patty O'Patrick O'Dell, who stated: "Many bridges and PCBs are green because they absorb red and blue light, only reflecting the green."

That wasn't quite what I was getting at, but close enough. The important thing, is that, generally, in commercial products, the PC boards are hidden, so the color doesn't matter that much. With prototypes and a lot of the hobby or development boards, that is not the case, so many companies have chosen to use a different color as a part of their identity.

Arduino products are blue, as are most boards from Adafruit. SparkFun makes theirs red. Ti Launchpads are red as well. The Beaglebone uses color, essentially, as a model number; Beaglebone black, Beaglebone green. This is possible because major PC board fab houses have made different colors more economical than they used to be.

I've been asked if the color makes any difference electrically. In general, no. If you're dealing with super high speeds, RF, or other exotic conditions, it's always best to ask your board house. In those fringe areas, a lot of things have the potential to make a difference. Other than that, if you can afford it, and want to make a statement, go for it. You can often get different color silk screen legend too. Just make sure there's contrast between the two. White silkscreen on white soldermask would not be the best choice.